This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Pathology Core provides professional histo-pathological tissue review and pathologist-guided tissue examination and description. This prominently includes staging of tumors appearing in model systems, grading of histopathologic malignant change (dysplasia) within these neoplastic tissues, quantification of the extent of tissue neoplastic or dysplastic change, and the extent of tissue plane invasion by these neoplastic/dysplastic cells. Two core directors, who are cancer biologists with, respectively, two and three decades of tumor biology experience, will work with target PIs, so they will provide adequate quality and numbers of experimental samples with proper control tissues for adequate histo-pathologic review. Tissue blocks and first cut slides provided by target PIs for pathological review from the Histology/Imaging Core Facility will be evaluated by the core director(s) and the Pathologist who will determine whether stained tissues sections are of adequate quality to proceed. If quality of the sections and their staining is adequate, full review will proceed. If the quality of fixation, embedding, sectioning and/or staining is not good enough, the blocks will be obtained, recut and restained until adequate quality is achieved and the best tissue areas are selected. The Pathology Core Facility will communicate with the project PI and mentors to learn about the molecular pathways being examined, in order to choose the best anatomic region most likely to express the most characteristic changes. The Facility will examine, photograph and describe the tissue and cell groupings most likely to express the biology of interest. Cells of intestinal crypts, normal mucosa, and adenomatous polyps may be identified and examined in several distinct areas in each paraffin embedded mouse tissue, and in several anatomic areas of the small and large bowel. The availability of the Pathology Core Facility will assure that all mouse lesions will be professionally examined, staged, graded, and categorized as to their malignant characteristics and potential, just as are colonic tissues and tumors obtained from human patients. The rigorous and consistent pathological interpretation of cancer-related changes in mouse tissues will add strength to all collaborative work fostered by the COBRE group.